This invention relates to the electrodeposition of tin, lead, and tin-lead alloys, and particularly to new compositions which are useful as additives in a plating bath for depositing smooth, level and bright tin and/or lead coatings. p
Aqueous acidic plating baths for depositing tin and/or lead coatings have been known in the art, and most of these baths contain, in addition to the water-soluble tin and/or lead salts, at least one radical selected from the group consisting of fluoborates, fluosilicates, sulfates, sulfamates, etc. In addition to these basic ingredients, the prior art has suggested improvements in such baths by including additives which will improve the brightness of the deposit obtained from such baths. In U.S. Pat. No. 3,875,029, the use of a naphthalene monocarboxaldehyde either alone or in combination with certain substituted olefins described in the patent results in an improvement in the brightness of the deposit. Other ingredients which have been suggested as being useful additives in tin and/or lead plating baths include various combinations of aldehydes, ketones, nonionic surfactants, and amines. For example, U.S. Pat. No. 3,769,182 describes the advantage of utilizing an alkoxylated fatty acid alkylolamide surfactant in tin and/or lead plating baths, and U.S. Pat. No. 3,749,649 describes the advantages of utilizing tin-lead plating baths containing at least one polyether surfactant and at least one aromatic aldehyde containing a chloro substituent. Another bath for producing bright deposits of tin-lead alloys is described in U.S. 3,785,939 and the U.S. Pat. No. system comprises a combination of a nonionic polyoxyalkylated surfactant, a lower aliphatic aldehyde, an aromatic aldehyde, and an amine. U.S. Pat. No. 4,000,047 describes a bath for depositing tin and tin-lead alloys which contain a lower alkylene oxide condensation product selected pyridine and quinoline compounds and aromatic aldehydes.